Sensible Heat Energy Storage System for Combined Hot Water - Steam Production Based on Cold - Heat Alternating Control Strategy

Abstract

The present invention discloses a sensible heat energy storage system and method for combined production of hot water and steam based on a cold and hot alternating control strategy, belonging to the technical field of sensible heat energy storage. The system includes a multi-stage water storage module composed of a cold water tank, a medium-temperature water tank, and a hot water tank, multiple energy storage devices filled with solid-phase heat storage materials, a header and a power valve / three-way valve assembly, and a steam drum; the control module dynamically switches the flow direction of the working medium according to the outlet temperature threshold of the energy storage device and the water level threshold of the water tank. During the heat charging process, the working medium is stored in the corresponding water tank according to the outlet temperature of the energy storage device, and the medium-temperature and high-temperature water tanks are used to preheat the modules with too low temperature; during the heat discharging process, the working medium in the cold water tank and the hot water tank is alternately switched into two or more energy storage devices, and the circulating heating is triggered in combination with the liquid level to achieve the stable combined production of hot water and steam. By means of multi-tank hierarchical storage and cold and hot alternating control, the present invention effectively suppresses the two-phase flow instability and improves the equipment life and the stability of output parameters.

Description

Technical Field

[0001] The present invention relates to a sensible heat energy storage system, and more particularly to a sensible heat energy storage system for combined production of hot water and steam based on a cold and hot alternating control strategy. Background Art

[0002] In the prior art, for a sensible heat energy storage system based on high-temperature resistant solid-phase materials (such as gravel, graphite, steel) and a shell-and-tube packed bed energy storage device, during the charging process, the heat of the heat-carrying fluid is transferred to the energy storage material through the heat exchange tubes for storage, and during the discharging process, the heat is transferred in the reverse direction for reuse.

[0003] Such systems are widely used in fields such as power generation and industrial preheating, but there are significant defects:

[0004] Due to the huge differences in density, compressibility, and viscosity between water and water vapor, two-phase flow instability is likely to occur in the heat exchange tubes, specifically manifested as severe oscillations in mass flow rate, pressure, and tube wall temperature, resulting in shortened equipment life, fluctuating outlet parameters, and unstable charging and discharging power. Although the prior art attempts to adjust by detecting the boundary of two-phase flow instability, affected by the dynamic change of heat flux caused by the temperature change of the energy storage material, this problem cannot be fundamentally solved. Summary of the Invention

[0005] The object of the present invention is to address the above problems existing in the prior art, and provide a sensible heat energy storage system for combined production of hot water and steam based on a cold and hot alternating control strategy. Through the coordinated control of a multi-tank structure (cold water tank, medium-temperature water tank, hot water tank) and a header-valve assembly, combined with a dynamic path switching strategy triggered by temperature thresholds (such as 70 °C, 120 °C, 170 °C) and liquid level thresholds (75%, 50% of the full scale), the two-phase flow instability is suppressed, and the stable combined production of hot water and steam is achieved, solving the problems that in the existing sensible heat energy storage system, the working medium parameters oscillate due to the two-phase flow instability of water vapor, it is difficult to achieve stable output, and it is impossible to efficiently produce hot water and steam simultaneously.

[0006] To achieve the above application object, the present invention adopts the following technical solutions: A sensible heat energy storage system for combined production of hot water and steam based on a cold and hot alternating control strategy includes:

[0007] A stratified water supply module, including a cold water tank, a medium-temperature water tank, and a hot water tank, for storing working media at different temperatures in stages, and during discharging, cold water and hot water alternately enter the high-temperature energy storage device for preheating the working medium and generating steam;

[0008] Multiple energy storage devices connected in parallel with the stratified water supply module, each energy storage device filled with a solid-phase sensible heat energy storage material inside, for exchanging heat with the heat-carrying fluid through heat exchange tubes;

[0009] Multiple headers, which are connected by pipelines to the stratified water supply module and the energy storage device, as well as between the energy storage device and the steam drum, are used for the distribution and collection of working medium and for the stacking of energy storage devices;

[0010] Multiple power valves and multiple three-way valves, which are arranged on the pipelines between the headers and each water tank and the energy storage device, are used for dynamically adjusting the flow direction of the working medium;

[0011] A steam drum, which is connected to the hot water tank and the headers corresponding to each energy storage device, is used for steam-water separation and outputting steam;

[0012] A control module, according to the outlet working medium temperature threshold of the energy storage device and the liquid level threshold of the water tank, triggers the opening and closing of the power valve and the three-way valve and switches the path, to realize the cold and heat alternating control in the heat charging stage and the heat discharging stage; configured as:

[0013] In the heat charging stage, distribute the working medium to the cold water tank, the medium-temperature water tank or the hot water tank according to the outlet working medium temperature of the energy storage device;

[0014] In the heat discharging stage, trigger the circulation of the working medium from the cold water tank or the hot water tank to the energy storage device according to the liquid level threshold, and re-distribute the working medium to the medium-temperature water tank, the hot water tank or the external steam drum based on the outlet working medium temperature threshold, to co-produce hot water and steam.

[0015] Further, the heat charging stage includes:

[0016] When the outlet working medium temperature of the energy storage device is lower than the first temperature threshold, the working medium flows to the cold water tank;

[0017] When the outlet working medium temperature of the energy storage device is between the first temperature threshold and the second temperature threshold, the working medium flows to the medium-temperature water tank;

[0018] When the outlet working medium temperature of the energy storage device is between the second temperature threshold and the third temperature threshold, the working medium flows to the hot water tank;

[0019] When there is an energy storage device with a temperature lower than the second temperature threshold or the third temperature threshold and not charged with high-temperature steam, use the working medium in the medium-temperature water tank or the high-temperature water tank to charge it (here, the module refers to preheating the module with too low temperature and not heated with steam using the medium-temperature or hot water tank).

[0020] Further, the first temperature threshold is 70 °C, the second temperature threshold is 120 °C, and the third temperature threshold is 170 °C.

[0021] Further, the liquid level threshold of the cold water tank is 75% of the full scale, and the liquid level thresholds of the medium-temperature water tank and the hot water tank are both 50% of the full scale. When the liquid level exceeds the liquid level threshold, trigger the opening of the corresponding power valve to discharge the working medium to the external circulation pipeline.

[0022] Further, the heat release end temperature threshold of the energy storage tank is 150 °C. When the average temperature is lower than this threshold, the system switches to the next energy storage tank to continue heat release.

[0023] Further, the filling material of the energy storage tank is a solid-phase sensible heat energy storage material, and the heat exchange tubes are copper tubes or stainless steel tubes.

[0024] Further, the operating pressure of the sensible heat energy storage system is 0.3 MPa for corresponding heat release and 1 MPa for corresponding heat charging. The working fluid circulation path is monitored and adjusted in real time through a pressure sensor.

[0025] To achieve the above application objectives, the present invention also adopts the following technical solutions:

[0026] A control method for a sensible heat energy storage system based on a hot water-steam co-production with a cold and hot alternating control strategy, comprising the following steps:

[0027] Heat charging stage control steps:

[0028] (a) Introduce high-temperature steam into the energy storage tank and detect the temperature of the working fluid at the outlet of the energy storage tank in real time;

[0029] (b) According to the comparison result between the temperature of the working fluid at the outlet and the preset temperature threshold, switch the path of the three-way valve to distribute the flow direction of the working fluid:

[0030] When the temperature of the working fluid at the outlet is lower than the first temperature threshold, direct the working fluid to the cold water tank;

[0031] When the temperature of the working fluid at the outlet is between the first temperature threshold and the second temperature threshold, direct the working fluid to the medium-temperature water tank;

[0032] When the temperature of the working fluid at the outlet is between the second temperature threshold and the third temperature threshold, direct the working fluid to the hot water tank;

[0033] (c) When the liquid level of the hot water tank exceeds 75% of the full scale, open the power valve corresponding to the hot water tank; when the liquid level of the medium-temperature water tank exceeds 75% of the full scale, open the power valve corresponding to the medium-temperature water tank; when the liquid level of the cold water tank exceeds 75% of the full scale, open the power valve corresponding to the cold water tank to discharge the working fluid and provide cold water to the external working fluid circulation pipeline;

[0034] Heat release stage control steps:

[0035] (d) Extract normal temperature water from the external circulation pipeline to the cold water tank to keep the liquid level of the cold water tank at 75% of the full scale. Extract normal temperature water from the cold water tank and input it into the energy storage tank, and monitor the liquid levels of the medium-temperature water tank and the hot water tank in real time;

[0036] (e) When the liquid level of the medium-temperature water tank exceeds 50% of the full scale, open the power valve corresponding to the medium-temperature water tank and introduce the working fluid into the external circulation pipeline for heat release;

[0037] (f)When the hot water tank liquid level exceeds 50% of the full scale, open the corresponding power valve of the hot water tank to deliver the working medium to the energy accumulator;

[0038] (g)According to the comparison results of the working medium temperature at the outlet of the energy accumulator with the steam generation threshold and the hot water generation threshold, dynamically adjust the working medium distribution:

[0039] When the hot water tank liquid level continuously exceeds 50% of the full scale during the heat release stage, alternately switch the three-way valve path at a set time period, so that the working medium circulation between two or more energy accumulators and the water supply system switches between the cold water tank and the hot water tank in an alternating order;

[0040] When using the working medium in the cold water tank and the heat storage device for circulation, distribute the working medium to the medium-temperature water tank or the hot water tank according to the working medium temperature at the outlet of the energy accumulator, where the working medium with the temperature at the outlet of the energy accumulator lower than the hot water generation threshold is distributed to the medium-temperature water tank, and the working medium with the temperature higher than or equal to the hot water generation threshold and lower than the steam generation threshold is distributed to the hot water tank;

[0041] When using the working medium in the hot water tank and the heat storage device for circulation, if the working medium temperature at the outlet of the energy accumulator reaches or exceeds the steam generation threshold, deliver the working medium to the steam drum for steam-water separation, output the separated steam, and return the hot water to the hot water tank;

[0042] If the working medium temperature at the outlet of the energy accumulator is lower than the steam generation threshold, re-distribute the working medium to the hot water tank for circulating heating.

[0043] Further, in the heat charging stage, multiple energy accumulators are charged in a preset order, collect the working medium with the outlet temperature higher than the temperature threshold into the medium-temperature water tank or the hot water tank, and use the medium-temperature and hot water tanks to preheat the modules with too low temperature; in the heat release stage, multiple energy accumulators are connected in parallel through the header and the water supply water tank, and dynamically distribute the working medium path according to the difference in the working medium temperature at the outlet of each energy accumulator. When using the hot water tank and the cold water tank to alternately provide circulating working medium for heat release, continuously output steam by using the steam drum, and the medium-temperature water tank outputs hot water.

[0044] Further, the first temperature threshold is 70 °C, the second temperature threshold is 120 °C, the third temperature threshold is 170 °C, the steam generation threshold is 133 °C, and the hot water generation threshold is 110 °C.

[0045] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0046] 1. Solve the problem of unstable two-phase flow:

[0047] Reduce the heat exchange tube wall temperature of the energy accumulator (such as from 330 °C to below 110 °C) through the cold water preheating stage, reduce the normal heat flux of the tube wall during hot water steam generation, and the experiment shows that the standard deviation of the outlet pressure is reduced by 50%, significantly weakening the parameter oscillation to achieve more stable steam supply to the outside.

[0048] 2. Achieve efficient co-production of hot water and steam:

[0049] The medium-temperature water tank directly provides stable hot water at ≤ 133°C (output when the liquid level ≥ 50%), and the steam drum separates high-quality steam (temperature ≥ 133°C), realizing the output of dual products and expanding the application scenarios.

[0050] 3. Modular expansion and efficient heat charging and discharging

[0051] The energy storage devices can be infinitely stacked and are flexibly configured in series / parallel through headers; during heat charging, they are stored by temperature grading (such as thresholds of 70°C → 120°C → 170°C), and during heat discharging, the high-temperature energy storage devices are preferentially used to generate steam, improving the energy utilization efficiency.

[0052] 4. Prolong the service life of the equipment:

[0053] The cold and heat alternating control strategy (such as switching the working fluid path every 10 minutes) avoids local overheating of the energy storage device, weakens problems such as water vapor impact corrosion inside the heat exchange tubes and pipeline vibration caused by the oscillation of the working fluid pressure and flow parameters inside the tubes, so as to improve the service life of the pipeline, and the system cycle life can be increased to more than twice that of the existing technology.

[0054] 4. Parameter adaptive optimization:

[0055] The heat charging and discharging pressure (0.3MPa / 1MPa) is linked with the temperature threshold to ensure the matching of the working fluid circulation path and the thermodynamic properties of the material, and the charging and discharging energy efficiency is significantly improved. Brief description of the drawings

[0056] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0057] Figure 2 is a graph of the parameter fluctuations inside the tube when the existing technology directly uses hot water for energy release;

[0058] Figure 3 is a graph of the standard deviation of the outlet pressure fluctuation changing with the time interval in the existing technology;

[0059] Figure 4 is a graph of the parameter fluctuations inside the tube during the cold and heat alternating energy release in the embodiment of the present invention;

[0060] Figure 5 is a graph of the standard deviation of the outlet pressure fluctuation changing with the time interval in the embodiment of the present invention.

[0061] In the figure, 1, 24, 26 - working fluid circulation pumps;

[0062] 2, 7, 30, 37, 39 - inlets and outlets of the external working fluid circulation pipeline;

[0063] 3, 10, 11, 12, 13, 14, 15, 16, 17, 18, 31, 32, 33, 34, 35, 36 - Power valve;

[0064] 4 - Cold water tank (normal temperature water tank);

[0065] 5 - Medium temperature water tank;

[0066] 6 - Hot water tank (high temperature water tank);

[0067] 8, 9, 20, 22, 23, 25 - Power three - way valve;

[0068] 19 - The first energy storage inlet header;

[0069] 21 - The Xth energy storage inlet header;

[0070] 27 - The first energy storage;

[0071] 28 - The Xth energy storage;

[0072] 29 - The first energy storage outlet header;

[0073] 38 - Steam drum;

[0074] 40 - The Xth energy storage outlet header;

[0075] 41 - Liquid level sensor;

[0076] 42 - Pressure sensor. Detailed implementation mode

[0077] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art belong to the scope of protection of the present invention.

[0078] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention.

[0079] Embodiment 1

[0080] As Figure 1As shown in the figure, the sensible heat energy storage system for combined production of hot water and steam based on the cold and hot alternating control strategy includes:

[0081] 1. Stratified water supply module

[0082] Cold water tank 4: Stores normal temperature water (≤70°C). It is not limited to water and can be other working fluids. It is connected to the external working fluid circulation pipeline inlet and outlet 2 and the energy storage devices (27, 28) through power valves (3, 13, 14). It is also connected to the medium temperature water tank 5 through a pipeline and power valve 11. Here, the energy storage devices (27, 28) do not refer to two energy storage devices (the same below), but the first energy storage device 27 and the Xth energy storage device 28, and the number of energy storage devices can be infinitely stacked.

[0083] Medium temperature water tank 5: Stores working fluid at 70°C - 120°C. It is connected to the energy storage devices (27, 28) and the external working fluid circulation pipeline inlet and outlet 7 through power valves (10, 15, 16). It is also connected to the power three-way valve 8, and at the same time is connected to the hot water tank 6 through power valve 12 and a pipeline.

[0084] Hot water tank 6: Stores working fluid at 120°C - 170°C. It is connected to the energy storage devices (27, 28) through power valves (17, 18), and is also respectively connected to the steam drum 38 and the power three-way valve 9.

[0085] 2. Energy storage module

[0086] Energy storage devices (27, 28): Filled with graphite (or gravel, refractory bricks), with copper pipes (diameter 18mm, length 1.5m) inside. They are stacked through the inlet headers (19, 21) and outlet headers (29, 40). Here, the inlet headers (19, 21) and outlet headers (29, 40) do not refer to two headers respectively, but the first energy storage device inlet header 19 and the Xth energy storage device inlet header 21, as well as the first energy storage device outlet header 29 and the Xth energy storage device outlet header 40. Each energy storage device is provided with an inlet header and an outlet header.

[0087] Inlet headers and outlet headers: Distribute the working fluid to each energy storage device to achieve modular expansion. For example, the first energy storage device inlet header 19 is respectively connected to the cold water tank 4, the medium temperature water tank 5, and the hot water tank 6 through power valves (13, 15, 17). The Xth energy storage device inlet header 21 is respectively connected to the cold water tank 4, the medium temperature water tank 5, and the hot water tank 6 through power valves (14, 16, 18). The first energy storage device outlet header 29 is respectively connected to the external working fluid circulation pipeline inlet and outlet 30, the steam drum 38, and the power three-way valve 8 through power valves (31, 32, 33). The Xth energy storage device outlet header 40 is respectively connected to the external working fluid circulation pipeline inlet and outlet 37, the steam drum 38, and the power three-way valve 9 through power valves (34, 35, 36).

[0088] 3. Valves and steam drum

[0089] Power valves (3, 10 - 18, 31 - 36): Control the on / off and flow direction of the working medium (e.g., power valves 13 - 18 control the path from the cold water tank to the energy accumulator). The number of power valves increases with the increase in the number of energy accumulators. Power valve 31 connects to the inlet and outlet 30 of the external working medium circulation pipeline, and power valve 34 connects to the inlet and outlet 37 of the external working medium circulation pipeline.

[0090] Power three - way valves (8, 9, 20, 22, 23, 25): Switch the flow - splitting path of the working medium (e.g., power three - way valves 23 and 20 control the working medium from the energy accumulator outlet to the cold water tank). Figure 1 Among them, power three - way valve 8 is respectively connected to power valve 33, medium - temperature water tank 5, and hot water tank 6; power three - way valve 9 is respectively connected to power valve 36, medium - temperature water tank 5, and hot water tank 6; power three - way valve 20 is respectively connected to the inlet header 19 of the first energy accumulator, working medium circulation pump 24, and power three - way valve 23; power three - way valve 22 is respectively connected to the inlet header 21 of the X - th energy accumulator, working medium circulation pump 26, and power three - way valve 25; power three - way valve 23 is respectively connected to the first energy accumulator 27, working medium circulation pump 24, and power three - way valve 20; power three - way valve 25 is respectively connected to the X - th energy accumulator 28, working medium circulation pump 26, and power three - way valve 22.

[0091] Steam drum 38: Communicates with the hot water tank 6 and the energy accumulator outlet headers (29, 40), separates steam (≥133°C) from hot water (≤133°C), and also connects to the inlet and outlet 39 of the external working medium circulation pipeline to supply steam to the outside.

[0092] Working medium circulation pumps (1, 24, 26): Serve as the power source to drive the flow of the working medium. For example, working medium circulation pump 1 is connected to the cold water tank 4, the two ends of working medium circulation pump 24 are respectively connected to power three - way valve 23 and power three - way valve 20, and the two ends of working medium circulation pump 26 are respectively connected to power three - way valve 22 and power three - way valve 25.

[0093] 4. Control module

[0094] Integrated temperature sensors (monitor the inlet and outlet of the energy accumulator and the temperature of the water tank), level sensor 41 (water tank level), and pressure sensor 42 (system pressure: 1 MPa for heat charging / 0.3 MPa for heat discharging) dynamically adjust the valve state through logical algorithms. Instruments such as pressure sensor 42, temperature sensor 41, exhaust valve, drain valve, and safety valve are arranged according to the layout method of a conventional thermal engineering system.

[0095] Embodiment 2

[0096] Based on the same concept, this embodiment provides a control method for a sensible heat energy storage system with combined production of hot water and steam based on a cold and hot alternating control strategy. When this energy storage system operates, there are two working fluid circulation paths during the charging and discharging processes. The following processes are the circulation paths of the working fluid and the valve control cases when the system is charging and discharging heat respectively:

[0097] I. During heat charging, the system operating pressure is 1 MPa:

[0098] 1. High-temperature superheated steam (1 MPa, 300 °C) enters the first energy storage tank 27 from the inlet and outlet of the external working fluid circulation pipeline 30.

[0099] 1.1 If the outlet temperature is lower than 70 °C after passing through the first energy storage tank 27, it will pass through the power three-way valve 23 → power three-way valve 20 → the first energy storage tank inlet header 19 → power valve 13 and enter the cold water tank 4.

[0100] 1.2 If the outlet temperature is lower than 120 °C and higher than 70 °C after passing through the first energy storage tank 27, it will pass through the power three-way valve 23 → power three-way valve 20 → the first energy storage tank inlet header 19 → power valve 15 and enter the medium-temperature water tank 5.

[0101] 1.3 If the outlet temperature is lower than 170 °C and higher than 120 °C after passing through the first energy storage tank 27, it will pass through the power three-way valve 23 → power three-way valve 20 → the first energy storage tank inlet header 19 → power valve 17 and enter the hot water tank 6.

[0102] 1.4 If the temperature of the medium-temperature water tank 5 is higher than the temperature of the Xth energy storage tank 28, the working fluid will flow from the medium-temperature water tank 5 through the power valve 16 → the Xth energy storage tank inlet header 21 → power three-way valve 22 → working fluid circulation pump 26 → power three-way valve 25 → the Xth energy storage tank 28 → the Xth energy storage tank outlet header 40 → power valve 34 and enter the inlet and outlet of the external working fluid circulation pipeline 37.

[0103] 1.5 If the temperature of the hot water tank 6 is higher than the temperature of the Xth energy storage tank 28 and the power valve 16 is not opened, the working fluid will flow from the hot water tank 6 through the power valve 18 → the Xth energy storage tank inlet header 21 → power three-way valve 22 → working fluid circulation pump 26 → power three-way valve 25 and enter the Xth energy storage tank 28; if the outlet temperature of the Xth energy storage tank 28 is higher than 40 °C, it will pass through the Xth energy storage tank outlet header 40 → power valve 36 → power three-way valve 9 and enter the medium-temperature water tank; if the outlet temperature of the energy storage tank is lower than 40 °C, it will pass through the header - power valve 34 and enter the inlet and outlet of the external working fluid circulation pipeline 37.

[0104] 2. If the outlet temperature is higher than 170 °C after passing through the first energy storage tank 27, the high-temperature steam will enter the Xth energy storage tank 28 from the inlet and outlet of the external working fluid circulation pipeline 37 of the Xth energy storage tank 28.

[0105] 2.1 If the outlet temperature is lower than 70°C after passing through the Xth energy storage device 27, then it enters the cold water tank 4 through the power three-way valve 25 → power three-way valve 22 → the inlet header 21 of the Xth energy storage device → power valve 14;

[0106] 2.2 If the outlet temperature is lower than 120°C and higher than 70°C after passing through the Xth energy storage device 27, then it enters the medium-temperature water tank 5 through the power three-way valve 25 → power three-way valve 22 → the inlet header 21 of the Xth energy storage device → power valve 16;

[0107] 2.3 If the outlet temperature is lower than 170°C and higher than 120°C after passing through the first energy storage device 27, then it enters the hot water tank 6 through the power three-way valve 25 → power three-way valve 22 → the inlet header 21 of the first energy storage device → power valve 18;

[0108] 3. If the liquid level of the hot water tank 6 exceeds 75% of the full scale, the power valve 12 opens; if the liquid level of the medium-temperature water tank 5 exceeds 75% of the full scale, the power valve 11 opens; if the liquid level of the cold water tank 4 exceeds 75% of the full scale, the power valve 3 opens, and the cold working medium provides cold water to the external working medium circulation pipeline through the inlet and outlet 2 of the external working medium circulation pipeline.

[0109] 4. If the outlet temperature of the high-temperature steam exceeds 170°C after passing through the Xth energy storage device 28, the heat charging ends.

[0110] The number of energy storage devices in this system can be countless. According to the heat charging logic provided in this case, the heat charging is carried out in sequence according to the order of the energy storage devices.

[0111] II. During heat release, the operating pressure of the system is 0.3 MPa:

[0112] 1. The normal-temperature water enters the cold water tank 4 through the power valve 3 at the inlet and outlet 2 of the external working medium circulation pipeline, and keeps the liquid level of the cold water tank 4 at 75% of the full scale. After the liquid level reaches, the cold working medium enters the first energy storage device 27 through the power valve 13 → header → No. 20 power three-way valve → working medium circulation pump 24 → power three-way valve 23;

[0113] 1.1 If the outlet temperature of the first energy storage device 27 is lower than 110°C, the working medium enters the medium-temperature water tank 5 through the outlet header 29 of the first energy storage device → power valve 33 → power three-way valve 8;

[0114] 1.2 If the liquid level of the medium-temperature water tank 5 exceeds 50% of the full scale, the power valve 10 opens, and the medium-temperature water tank 5 can provide hot water to the external working medium circulation pipeline through the inlet and outlet 7 of the external working medium circulation pipeline;

[0115] 1.3 If the outlet temperature of the first energy storage device 27 is higher than 110°C and lower than 133°C, the working medium enters the hot water tank 6 through the outlet header 29 of the first energy storage device → power valve 33 → power three-way valve 8;

[0116] 2. If the liquid level of the hot water tank 6 is higher than 50% of the full scale, the working fluid in the cold water tank 4 and the working fluid in the hot water tank 6 will have a fixed alternating cycle of 120 s. The cold working fluid will flow periodically and alternately through the power valves 13 and 17 or power valves 14 and 18 → the first energy storage inlet header 19 or the Xth energy storage inlet header 21 → the 20th power three-way valve or the 22nd power three-way valve → the working fluid circulation pump 24 or 26 → the power three-way valves 23 or 25 and enter the first energy storage 27 or the Xth energy storage 28 at a high flow rate (2000 kg / h), and the hot working fluid will enter at a low flow rate (300 kg / h).

[0117] 2.1 If the first energy storage is in the cold working fluid cycle of the cycle, and the Xth energy storage is in the hot working fluid (steam generation) cycle of the cycle;

[0118] 2.1.1 If the outlet temperature of the first energy storage 27 is lower than 110 °C, the working fluid will pass through the first energy storage outlet header 29 → the power valve 33 → the power three-way valve 8 and enter the medium-temperature water tank 5;

[0119] 2.1.2 If the outlet temperature of the first energy storage 27 is higher than or equal to 110 °C and lower than 133 °C, the working fluid will pass through the first energy storage outlet header 2 → the power valve 33 → the power three-way valve 8 and enter the hot water tank 6;

[0120] 2.1.3 If the outlet temperature of the Xth energy storage 27 is higher than or equal to 133 °C, the working fluid will pass through the Xth energy storage outlet header 40 → the power valve 35 and enter the steam drum 38 for steam-water separation;

[0121] 2.1.4 The hot water in the steam drum 38 will re-enter the hot water tank 6;

[0122] 2.1.5 The steam in the steam drum 38 will enter the external working fluid circulation pipeline inlet and outlet 39 to supply steam to the outside world;

[0123] 2.1.6 If the outlet temperature of the Xth energy storage 27 is lower than 133 °C, the working fluid will pass through the Xth energy storage outlet header 40 → the power valve 36 → the power three-way valve 9 and enter the hot water tank;

[0124] 3. If the average temperature of the first energy storage 27 is lower than 150 °C, the heat release of the first energy storage 27 will end, and the Xth energy storage and other energy storages in the system will start the cold and hot alternating heat release process until the number of energy storages with a temperature higher than 150 °C in the system is less than 2, then the heat release of the system will end.

[0125] When two or more energy storages release heat according to the cold and hot alternating control strategy, the number of energy storages can be an even number or an odd number.

[0126] This case provides a heat energy release process in accordance with the cold and hot alternating logic in the order of energy storage devices, in which the steam-water separation process in the steam drum is the same as that of common thermal equipment. The core innovation of the present invention is that in the second step, two or more energy storage devices are used to release heat according to the control logic of alternating cold and hot working media, and three water tanks of normal temperature (cold) - medium temperature - high temperature (hot) are set in the system, thereby suppressing the occurrence of two-phase flow instability in the steam production process, and continuously providing steam with more stable export parameters to the outside world; and while generating steam, the medium-temperature water tank 5 is used to provide hot water with a temperature below 133°C to the outside world.

[0127] In order to verify the technical effect of the hot and cold alternating heat release strategy in the present invention, Figure 2 As shown, the size is 0.15*0.15*1.5m, graphite is used as the heat storage material, and a packed bed with a copper tube of 18mm in diameter and 1.5m in length is built horizontally. The heat release starting temperature is 330℃. Under normal working conditions, steam generation and heat release continue after the module is charged. Figure 2 The fluctuation curves of the outlet pressure, mass flow rate and inlet temperature of the packed bed when 95℃ hot water is used as the working fluid for heat release at normal pressure are shown. It can be seen that obvious parameter fluctuations are caused by the instability of the two-phase flow. Figure 3 A curve of the standard deviation of the outlet pressure changing with time is calculated every 60 seconds.

[0128] like Figure 4 As shown in the figure, the fluctuation curve of the parameters in the tube is that the heat is released by using the cold and hot alternating energy release scheme with an alternating cycle of 180s. The time ratio of the cold water preheating and the hot water steam production process is 1:1. Figure 5 The standard deviation of the outlet pressure when the outlet pressure fluctuates in each hot water heat release cycle during hot water steam production. The X-axis is the sequence number of each alternating cycle sorted by time. During the cold water preheating stage, the cold water valve is opened, the water flow increases, the hot water steam production circulation pipeline is switched to the bypass, and the hot water flow increases; when hot water steam is produced, its pipeline is switched to the steam production circulation path, the hot water flow decreases and steam production begins, and the cold water valve is closed.

[0129] By comparison Figure 5 and Figure 3 It can be seen that the standard deviation of the outlet pressure is reduced by 50% in the early stage of energy release when using the hot and cold alternating scheme of the present invention.

[0130] The parts not described in detail in the present invention are prior art, so the present invention does not describe them in detail.

[0131] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0132] Although this text uses many professional terms, it does not exclude the possibility of using other terms. The use of these terms is only for the convenience of describing and explaining the essence of the present invention; interpreting them as any additional limitation is contrary to the spirit of the present invention.

[0133] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can obtain other various forms of products under the inspiration of the present invention. However, no matter what changes are made in its shape or structure, as long as it has a technical solution identical or similar to that of the present invention, it falls within the protection scope of the present invention.

Claims

1. A hot water-steam cogeneration sensible heat energy storage system based on a hot and cold alternating control strategy, characterized in that: include: The stratified water supply module includes a cold water tank, a medium-temperature water tank and a hot water tank, which are used to store working fluids of different temperatures in stages. When releasing heat, cold water and hot water alternately enter the energy storage device to preheat the working fluid and produce steam. Cold water enters the energy storage device to preheat the working fluid to generate medium-temperature / hot water, and hot water enters the energy storage device to produce steam. A plurality of energy storage devices connected in parallel with the stratified water supply module, each of which is filled with a solid-phase sensible heat storage material for exchanging heat with a heat-carrying fluid through a heat exchange tube; Multiple headers are connected to the stratified water supply module and the accumulator, and the accumulator and the steam drum through pipelines, and are used for the distribution and collection of working fluids, and for the superposition of accumulators; A plurality of power valves and a plurality of three-way valves are arranged on the pipeline between the manifold and each water tank and energy storage device, and are used to dynamically adjust the flow direction of the working medium; The steam drum is connected to the hot water tank and the header corresponding to each accumulator, and is used for steam-water separation and steam output; Control module, configured as: In the charging stage, the working fluid is distributed to the cold water tank, the medium temperature water tank or the hot water tank according to the working fluid temperature at the outlet of the energy storage device; During the heat release phase, the circulation of the working fluid from the cold water tank or hot water tank to the energy storage is triggered according to the liquid level threshold, and the working fluid is redistributed to the medium-temperature water tank, hot water tank or external steam drum based on the outlet working fluid temperature threshold to co-produce hot water and steam.

2. The sensible heat storage system for hot water-steam cogeneration based on the hot and cold alternating control strategy according to claim 1 is characterized in that: The heating stage includes: When the working fluid temperature at the outlet of the energy storage device is lower than the first temperature threshold, the working fluid flows to the cold water tank; When the working fluid temperature at the outlet of the energy storage device is between the first temperature threshold and the second temperature threshold, the working fluid flows to the medium temperature water tank; When the working medium temperature at the outlet of the energy storage device is between the second temperature threshold and the third temperature threshold, the working medium flows to the hot water tank; When there is an energy storage device whose temperature is lower than the second temperature threshold or the third temperature threshold and which is not charged with high-temperature steam, the energy storage device is charged with the working fluid in the medium-temperature water tank or the high-temperature water tank.

3. The sensible heat storage system for hot water-steam cogeneration based on the hot and cold alternating control strategy according to claim 2 is characterized in that: The first temperature threshold of the heating stage is 70°C, the second temperature threshold is 120°C, and the third temperature threshold is 170°C.

4. The sensible heat storage system for hot water-steam cogeneration based on the hot and cold alternating control strategy according to claim 2 is characterized in that: During the heat release stage, the liquid level threshold of the medium-temperature water tank and the hot water tank is 50%, which is dynamically adjusted according to the charging and discharging stages; when the liquid level exceeds the liquid level threshold, the corresponding power valve is triggered to open to discharge the working fluid into the external circulation pipeline.

5. The sensible heat storage system for hot water-steam cogeneration based on the hot and cold alternating control strategy according to claim 1 is characterized in that: The energy storage device heat release end temperature threshold is 150° C. When the average temperature is lower than the threshold, the energy storage device is switched to the next energy storage device to continue heat release.

6. The sensible heat storage system for hot water-steam cogeneration based on the hot and cold alternating control strategy according to claim 1 is characterized in that: The energy storage device filling material is a solid-phase sensible heat energy storage material, and the heat exchange tube is a copper tube or a stainless steel tube.

7. The sensible heat storage system for hot water-steam cogeneration based on the hot and cold alternating control strategy according to claim 1 is characterized in that: The operating pressure of the sensible heat energy storage system is 0.3 MPa corresponding to heat release and 1 MPa corresponding to heat charging, and the working fluid circulation path is monitored and adjusted in real time through a pressure sensor.

8. The control method of the hot water-steam cogeneration sensible heat energy storage system based on the hot and cold alternating control strategy of claim 1 is characterized in that: The following steps are involved: Control steps of heating stage: (a) High-temperature steam is introduced into the energy storage device to detect the outlet working fluid temperature of the energy storage device in real time; (b) According to the comparison result between the outlet working fluid temperature and the preset temperature threshold, the three-way valve path is switched to allocate the working fluid flow direction: When the outlet working fluid temperature is lower than a first temperature threshold, directing the working fluid to a cold water tank; When the outlet working fluid temperature is between the first temperature threshold and the second temperature threshold, directing the working fluid to the medium temperature water tank; When the outlet working fluid temperature is between the second temperature threshold and the third temperature threshold, directing the working fluid to the hot water tank; (c) When the liquid level in the hot water tank exceeds 75% of the full scale, the power valve corresponding to the hot water tank is opened; when the liquid level in the medium temperature tank exceeds 75% of the full scale, the power valve corresponding to the medium temperature tank is opened; when the liquid level in the cold water tank exceeds 75% of the full scale, the power valve corresponding to the cold water tank is opened to discharge the working fluid and provide cold water to the external working fluid circulation pipeline; Exothermic stage control steps: (d) Pumping normal temperature water from the external circulation pipeline into the cold water tank, maintaining the liquid level of the cold water tank at 75% of the full scale, pumping normal temperature water from the cold water tank into the energy storage device, and monitoring the liquid levels of the medium temperature water tank and the hot water tank in real time; (e) When the liquid level of the medium temperature water tank exceeds 50% of the full scale, the power valve corresponding to the medium temperature water tank is opened to introduce the working fluid into the external circulation pipeline for heat release and provide hot water to the outside; (f) When the liquid level in the hot water tank exceeds 50% of the full scale, the power valve corresponding to the hot water tank is opened to transport the working fluid to the energy storage device; (g) Dynamically adjust the working medium distribution according to the comparison results between the working medium temperature at the outlet of the energy storage device and the steam generation threshold and the hot water generation threshold: When the liquid level in the hot water tank continuously exceeds 50% of the full scale during the heat release stage, the three-way valve path is switched alternately at a set time cycle, so that the working medium circulation between two or more energy storage devices and the water supply system is switched between the cold water tank and the hot water tank in an alternating order; When the working fluid in the cold water tank and the heat storage are circulated, the working fluid is allocated to the medium-temperature water tank or the hot water tank according to the working fluid temperature at the outlet of the energy storage device, wherein the working fluid with a working fluid temperature at the outlet of the energy storage device lower than the hot water generation threshold is allocated to the medium-temperature water tank, and the working fluid with a working fluid temperature higher than or equal to the hot water generation threshold and lower than the steam generation threshold is allocated to the hot water tank; When the working fluid in the hot water tank and the heat storage are circulated, if the working fluid temperature at the outlet of the heat storage reaches or exceeds the steam generation threshold, the working fluid is transported to the steam drum for steam-water separation, the separated steam is output, and the hot water is returned to the hot water tank; If the working fluid temperature at the outlet of the energy storage device is lower than the steam generation threshold, the working fluid will be redistributed to the hot water tank for circulation heating.

9. The control method according to claim 8, characterized in that: During the charging stage, multiple energy storage devices are charged in sequence according to a preset order, and the working fluid with an outlet temperature higher than the temperature threshold is collected into a medium-temperature water tank or a hot water tank, and the medium-temperature and hot water tanks are used to preheat the modules with too low temperatures. During the heat release stage, multiple energy storage devices are connected in parallel through a header and a water supply tank, and the working fluid path is dynamically allocated according to the temperature difference of the working fluid at the outlet of each energy storage device. When the hot water tank and the cold water tank are used to alternately provide circulating working fluid for heat release, the steam drum is used to continuously output steam, and the medium-temperature water tank outputs hot water.

10. The control method according to claim 8, characterized in that: The first temperature threshold of the heat charging stage is 70°C, the second temperature threshold is 120°C, and the third temperature threshold is 170°C. The steam generation threshold of the heat release stage is 133°C, and the hot water generation threshold is 110°C.

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